F^(-)在方解石表面的吸附及其对方解石表面性质的影响

Adsorption of F^(-)on Calcite Surface and Its Effect on Calcite Surface Properties

氟元素主要存在于磷矿和萤石等矿物中,这些矿物中都伴生有方解石脉石矿物,在浮选分离的弱酸条件下,矿物表面的F^(-)会部分溶出并吸附到矿物表面,从而影响矿物表面性质。本文研究了F^(-)在方解石表面的吸附及其对方解石表面性质的影响机理。结果表明,在矿浆pH值为5.5时,F^(-)以化学吸附的方式吸附在方解石表面,随着吸附时间的增加吸附量逐渐增加,90 min时方解石对F^(-)的吸附达到平衡。在油酸钠(NaOL)为捕收剂时,F^(-)的存在会降低方解石表面的疏水性。通过Zeta电位测试、溶液化学计算和X射线光电子能谱仪(XPS)分析表明,F^(-)会和方解石表面的Ca^(2+)反应生成CaF_(2)沉淀,占据方解石表面的Ca位点,降低NaOL在方解石表面的吸附量。

Fluoride mainly exists in minerals such as phosphate rock and fluorite,which are associated with calcite gangue minerals.Under the condition of the flotation separation of the weak acid,mineral surface of F^(-)will be partically dissolved and adsorbed to the mineral surface,thus affecting the mineral surface properties.The adsorption behavior of F^(-)on calcite surface and the effect of F^(-)on calcite surface properties were studied in this paper.The results show that F^(-)is adsorbed on calcite surface by chemisorption at 5.5 pH value of calcite pulp,and the adsorption amount increases gradually with the increase of time,and F^(-)adsorption by calcite reaches equilibrium at 90 min.When sodium oleate(NaOL)is used as collector,the presence of F^(-)weakens the hydrophobicity of calcite surface.Zeta potential test,solution chemistry calculation and X-ray photoelectron spectroscopy(XPS)analysis show that the F^(-)reacts with Ca^(2+)on calcite surface to form CaF_(2)precipitation,which occupies Ca sites on calcite surface and reduces the adsorption of NaOL on calcite surface.